The back-up plan is in case regulators find issues with lithium batteries after the 787 troubles

In the wake of Boeing's 787 Dreamliner issues, Airbus said it's prepared to redesign or utilize alternatives to its A350 lithium-ion jet batteries.

Airbus expects to use lithium-ion batteries much like those used in the 787 Dreamliner, but with recent battery fires occurring in the 787 jets, Airbus is ready to make any necessary changes that authorities may require.

Airbus has addressed that fires could be a potential threat when using lithium-ion batteries, but feels safe with its designs enough to continue with efforts to use them.

"We identified this fragility at the start of development and we think we resolved it about a year ago," said Fabrice Bregier, Airbus CEO. "Nothing prevents us from going back to a classical plan that we have been studying in parallel.

"We have a robust design. If this design has to evolve, we have the time to do that. If it has to change in a more drastic way because the authorities reach the conclusion that the technology is not mature, then we have all the time we need to do this on the A350 before first delivery in the second half of 2014."

The 787's lack of fire-fighting system has been the subject of inspection over the last week, but Airbus declined to offer any details regarding the A350's fire-fighting system or on the battery's design overall.

Throughout January 2013, 787 Dreamliner jets through Japanese airlines All Nippon Airways (ANA) and Japan Airlines (JAL) had various issues concerning the lithium-ion batteries. The 787s were grounded in the U.S., Japan and India while an investigation began.

Another downside is that LifePO batteries' voltage during discharge behaves like NiMH which isn't good as they'll keep their nominal voltage during almost the whole discharge and then just fall off the cliff. This makes it hard to tell how much the cell is actually charged/discharged. LiIon/Lipo batteries voltages go down linearly during discharge so it's easier in that respect.

Voltage stability is easily resolved with a supercap (although I doubt THEY are FAA approved) but your right the real issue is voltage drop. The battery in the 787 is subject to massive power draw on takeoff, this might not be met with LifePO.

LiPo and LiFePo have much better high power capability than Liion at the expense of capacity. This is why they are used in power tools and electric cars like the volt rather than cheaper, longer running liion.

quote: Another downside is that LifePO batteries' voltage during discharge behaves like NiMH which isn't good as they'll keep their nominal voltage during almost the whole discharge and then just fall off the cliff. This makes it hard to tell how much the cell is actually charged/discharged. LiIon/Lipo batteries voltages go down linearly during discharge so it's easier in that respect.

So what Lithium Iron Phosphate behaves like Nickel Metal Hydride during discharge. LiFePO4 are safer than Lithium Ion batteries. LiFePO4 may require more research to create a proper circuitry to keep the discharge and charge rates predictable. Lithium Ion will require more protective shell so if it does explode on impact it will not cause too much harm. If I am a passenger, I would vote for LiFePO4 because it is safer instead of Lithium Ion being easier for the engineer to use in a circuit.

When I read or heard of a vehicle or plane using Lithium Ion batteries, it feels like I am sitting on a bunch of bombs. I am a worried of cellphone and notebook computer using Lithium Ion batteries. These devices do have a history of becoming like bombs just by accident.